Multiple sclerosis (MS) is an autoimmune demyelinating disease of the CNS white matter resulting in conduction block and eventual axonal transection. Remyelination after injury occurs spontaneously and results in repair and functional recovery but is inefficient, particularly in the later stages of the disease. While treatments targeting the immunological component of MS have been developed, there has been less progress in the generation of therapies to enhance remyelination of axons. Thus, a key goal in MS research is the design and translation to the clinic of therapies that promote remyelination. Oligodendrocyte progenitors (OLP) are the main reservoir of myelinating and remyelinating cells in the CNS. Their differentiation into myelinating oligodendrocytes (OL) is a rate-limiting step in lesion repair in MS. Thus, understanding the OL differentiation and maturation pathway is vital to developing new treatments for demyelinating disorders. OLP differentiation occurs via a step-wise intrinsic transcriptional program, which can be modulated by pro-myelinating extrinsic factors; however the complex dynamics of this program are not fully characterized. Understanding the mechanisms that regulate the intrinsic program of differentiation may identify new strategies to enhance repair. Importantly, our lab recently identified the transcriptional activator, Krppel-like factor 6 (Klf6), as an essential coordinato of CNS myelination. Notably, Klf6 over-expression accelerates maturation, while Klf6 deletion in vitro or in vivo disrupts important steps in differentiation, leading to profound failure of CNS myelination. Effects of Klf6 are restricted to the differentiation program - inactivation in proliferating or mature cells produces no pathology. Our data further propose an important role for Klf6 in adults, critically, in remyelination. Klf6 is strongly induced in remyelinating lesionsand by extrinsic pro-myelinating factors associated with remyelination in MS. To understand its mechanism of action in promoting OL differentiation, we have conducted genome-wide analysis of chromatin occupancy of Klf6 and its transcriptional profile. This has identified a program of novel and anticipated Klf6- regulated genes. Excitingly, many of these are homeobox genes, important regulators of differentiation in cell types throughout the body. This suggests that Klf6 activates a novel set of machinery to promote differentiation and myelin formation. This proposal aims to determine how Klf6 works to promote myelination and if similar mechanisms are important for remyelination as well. I will test the central hypothesis that Klf6 modulation of the intrinsic differentiation program via homeobox factors is essential for CNS myelination and remyelination in two Specific Aims. In Aim 1, I will define the critical downstream targets of Klf6 and in Aim 2, I will determine the role of Klf6 and its downstream effectors in remyelination. This work will define a novel mechanism for myelin formation, and which may also be vital for its repair.